The invention relates to the field of housings for electrical circuit boards and more particularly to a box-shaped, electronic circuit assembly with a front cover and screw terminal connections for external cable located in the front of the assembly, whereby the individual cable lead access holes for the screw terminals are accessed by means of a frontal longitudinal channel.
An assembly similar to this type is known from Federal Republic of Germany published application 2,904,012. In that assembly forward projecting mechanical caps are mounted solidly, and the assembly is equipped with openings allowing the insertion of terminal plugs. On the left front side a lateral connection block is provided containing a multipolar contact strip with screw terminals for the reception of external leads. Each of these screw terminals directs the cap inwards towards the contacts, which connect at insertion with the appropriate mating contacts mounted laterally on the contact strip. The cover is solidly attached to the contact strip. In that assembly, however, the lead channel is not shielded by its cover.
The above-described arrangement can be improved, by keeping the easy frontal connection feature and by adding enough room for labeling. Further, for the purpose of clear visual access, the assemblies should be able to be mounted immediately next to each other, with adjacent flat sides, while retaining the easy plug-in connection feature. Lastly, a reliable and precise mechanism for effecting a plug connection without incurring undue additional costs is desired.
These objects are achieved when: a longitudinal cable channel is provided at the front of the assembly; a cover assembly includes a labeling surface; the cover assembly further shields the longitudinal channel and screw terminals; the screw terminals are connectable by means of a plug unit to an assembly containing a printed-circuit; and, a plug rail of the plug unit is connected electrically and mechanically to the circuit board and is equipped with a pivot for the plug unit.
In the arrangement known from U.S. Pat. No. 3,992,654, the pressure of the pivoting plug unit is absorbed by the outer frame, which means that the circuit boards, which are each attached to the frame, are forced to make an undesired relative movement with respect to the pivot swivel axis.
It is an object of this invention to make it impossible for there to be an undesired relative movement between a circuit board and the pivot axis of a plug unit through connecting parts. This is accomplished by the attachment of the pivot axis to the circuit boards.
The locating of a cable receiving space in a longitudinal channel of the plug unit has been shown to have advantages when the design allows the side wall opposite to the screw terminals connectors to be removed. A free access path for insertion of the leads is hereby preserved. In the invention shown in U.S. Pat. No. 3,992,654, a separate cover must be removed and the accessibility to the screw terminals is reduced because of the attachment angle of that separate cover.
In order to facilitate the insertion and the removal of the electrical lead unit, it is desirable to provide an attachment screw mounted on an axially unmovable bearing which is positioned on the opposite side of the electrical unit and which can be screwed into a thread in the molding of the plug unit.
A certain arrangement in the markings for the LEDs in the labeling panel is obtained when the longitudinal channel is flanked by screw connections and bordering LEDs, whereby the labeling panel, when in operation, is directly next to the LEDs. Since the LEDs should be more or less at the same height as the screw connections, but the circuit board can only start behind the screw connections, it is desirable to arrange the LEDs in a holder which is electrically and mechanically connected to the circuit board.
It is desirable to have a procedure to put the LEDs in place in one single action during the assembly of the circuit board.
To make sure that adjustment and testing is only performed by qualified personnel and in order to have the surface subassemblies always in an electrically isolated state, it is desirable to provide a module which is behind the plug unit as seen from the front and accessible after the plug unit has been pivoted away, which is accessible from the front attached to the assemblies for the fuse changing and/or adjusting of operation and measurement values.
To eliminate the outside stresses which the module might be subjected to, for example, by the changing of fuses in the circuit board, it is further advantageous to connect the module to the circuit board with dovetail connections and to depress it fully against its stops.
Accordingly, it is also an object of this invention to provide a box-shaped electrical assembly with improved accessibility for construction and repair. It is a further object of this invention to provide an attachment screw mounted on an axially rigid bearing to facilitate the insertion and the removal of the electrical unit. It is another object of this invention to arrange the LEDs in a holder that is electrically and mechanically connected to the circuit board of the assembly, and to assemble the LEDs in place by a single-action procedure. It is another object of this invention to provide a fusing and/or adjustment subassembly module mounted behind the plug unit for service and adjustment by qualified personnel.